Everything HydroSewer does
Every capability below is available in the app today. Each one runs entirely on your device.
Import & export .inp
Full round-trip with the EPA SWMM 5 file format and a native project format.
- Import EPA SWMM 5 .inp input files
- Open native .hydrosewer project files
- Parses all standard SWMM sections — [OPTIONS], [JUNCTIONS], [CONDUITS], [SUBCATCHMENTS], [POLYGONS] and more
- File-format validation with graceful handling of malformed files
- Export edited networks back to .inp
- Save projects in the native .hydrosewer format
The real SWMM 5 engine, on-device
The actual EPA SWMM 5 computational engine runs locally via FFI — no server, no cloud.
- Runs the real EPA SWMM 5 engine on your device
- Simulation runs in a background isolate, off the UI thread
- Pre-simulation validation checks for an outfall, links and isolated nodes before running
- Clear validation error messages when a network is not ready
- Progress indicators during execution
- Runs on iOS, Android and macOS
Network editing & creation
Build and modify sanitary and storm sewer networks directly on the canvas.
- Edit node properties: invert elevation, max / initial / surcharge depth, ponded area, inflow, outfall type
- Edit link properties: conduit length, roughness, shape and diameter, plus pump, orifice, weir and outlet settings
- Edit subcatchment properties: area, width, slope, % impervious, roughness, depression storage and infiltration (Horton, Green-Ampt, Curve Number)
- Add junctions, outfalls, storage units, conduits and pumps by tapping the canvas
- Move mode: drag nodes to reposition — connected links follow in real time
- Delete mode with confirmation and cascade delete of connected links
- Auto-generated IDs, duplicate checking and auto-calculated link length
- Live validation of ID uniqueness, node references and numeric input, with an unsaved-changes badge
Interactive network canvas
Zoom, pan and inspect every element — including subcatchments, unique to SWMM.
- Interactive canvas: zoom, pan and navigate the network
- Color-coded nodes (junction, outfall, storage, divider) and directional links (conduit, pump, orifice, weir, outlet)
- Subcatchment polygons for rainfall-runoff areas — unique to SWMM
- Semantic zoom keeps elements a constant visual size, with smooth real-time repaint during gestures
- Fit-to-screen and zoom in / out controls
- Tap to select elements and see a quick properties card
- Live network statistics: element counts, bounds and zoom level
Simulation results
Read hydraulic results for every node, link and subcatchment across all timesteps.
- Node results: depth, head, volume, lateral inflow and flooding
- Link results: flow, velocity, depth and capacity
- Subcatchment results: runoff, infiltration and evaporation
- Every timestep saved as time-series data
- Mass-balance continuity error reporting
Results visualization
Color-coded maps and a scrubbable timeline make results easy to read in the field.
- Nodes color-coded by depth: blue → green → orange → red
- Links color-coded by flow capacity
- Flooded and surcharging nodes highlighted
- Interactive timeline to scrub through simulation timesteps
- Color legend to interpret every result color
- Light and dark themes that follow your OS preference
Units, both systems
US Customary and Metric, detected from your model and applied everywhere.
- US Customary units (ft, ft², ft³/s, …)
- Metric / SI units (m, m², m³/s, …)
- Auto-detected from the FlowUnits in your .inp file
- Dynamic unit labels across the whole interface
100% offline & private
The release build ships with no internet permission — your models never leave the device.
- Works with no connection — the release build requests no internet permission
- No account, no sign-in required
- No analytics, no telemetry and no crash reporting
- Your networks, models and results stay in local files on your device
Field notes & photos
Close the loop between the model and what is actually in the ground — free and unlimited.
- Notes on junctions, outfalls, storage, dividers and conduits, each Open or Resolved
- Photos from the camera or the gallery, with a zoomable full-screen viewer
- The same photo is stored once, and images are downscaled on import to keep the file small
- An amber ring marks every element that has notes — always visible on the canvas, not only in Notes Mode
- Notes Mode: tap an element and go straight to its notes
- One project-wide list of every open note, newest first, tap to jump to the element
- Notes and photos live in the .hydrosewer package and are never written to the .inp
Reports & saved projects
Turn open notes into a document, and get back to yesterday’s project in one tap.
- PDF report of the open notes — element, note, date and photo count — with the EPA/SWMM disclaimer
- Share or print it through the system sheet
- The PDF report is the one thing HydroSewer Pro adds; notes and photos stay free forever
- Saved Projects: reopen a recent project without the file picker
- Saving asks for a name and warns you before overwriting
In the works, not yet released
These are being built and are not available in the current release. We list them here so you know what's next — not as features you can use today.
GPS-tagged notes
Stamp a note with your real position in the field and let the app pick the nearest element. The data model and the geometry are in place; the location capture itself is not wired yet.
Place a note by tapping the map
Drop an observation anywhere on the canvas, not only on an existing node or pipe. Designed, not yet implemented.
Field ↔ office sync
Stable element IDs and delete tombstones already make the format sync-ready, so a crew in the field and the office could share one project. There is no sync backend yet.
Sizing a pipe instead?
Sewer Pipe Calculator
The other half of the job: sizing. Diameter, slope, velocity and depth with Manning, and a gravity collector laid out segment by segment. No network model, no simulation engine.
Put SWMM 5 in your pocket
Available now on the App Store and Google Play — model sewer and stormwater networks offline, wherever the work takes you.